Hobbing machine



Jan. 16, 1951 T. F. CARLIN 2,537,967

HOBBING MACHINE Filed Sept. 22, 1944 3 Sheets-Sheet l T. F. CARLINHOBBING MACHINE Jan. 16, 1951 3 Sheets-Sheet 3 Filed Sept. 22, 1944INVENTOR. 72500025 CflEL/N Patented Jan. 16, 1951 HOBBING MACHINETheodore F. Carlin, Cleveland, Ohio, assignor to The Cleveland HobbingMachine Company, Euciid, Ohio, a corporation of Ohio ApplicationSeptember 22,1944, Serial No. 555,246

18 Claims.

The present invention relates to bobbing machines and, moreparticularly, to hobbing machines of the axial feed type asdistinguished from tangential feed type bobbing machines.

In the operation of hobbing machines of the axial feed type, it hasheretofore been customary to periodically advance the hob, that is movethe hob tangentially of the work spindle after a number of blanks havebeen cut so as to bring a new section of the hob into cutting position.This practice does not make full use of the hob since the portionsthereof intermediate successive settings performed very little, if any,cutting; in other words, the wear, etc., incident to the cuttingoperation being performed is not uniformly distributed over the usableor effective length of the hob.

The principal object of the present invention is the provision of anovel and improved hobbing machine or hob head comprising means forcontinuously advancing the hob or moving it tangentially of the workduring the operation of the machine in such a manner that the hob isadvanced an amount equal to its usable r efiective length once duringsome relatively long predetermined period, such as a work day, a halfday, or the like. At the end of each period the hob is replaced, ifnecessary, and the direction of advance reversed or the mechanismreturned to its original position and the cycle repeated. A1-ternatively, the hob may be intermittently advanced a very small amountbetween the cutting operations.

Another object of the invention is the provision of a novel and improvedbobbing machine of the axial feed type comprising means for continuouslyadvancing the hob or moving the same axially at a very slow rate duringoperation of the machine, which means will be simple in construction,positive, reliable and accurate in operation, and preferably includesmechanism for readily disconnecting the same when its use is notdesired.

The invention resides in certain constructions and combinations andarrangements of parts and further objects and advantages will beapparent from the following description of the preferred embodimentdescribed with reference to the accompanying drawings forming a part ofthis specification, in which similar reference characters de gnatecorresponding parts, and in which 1 is a perspective view of a bobbingmachine embodying the present invention;

Fig. 2 is a sectional view, with portions in elevation, through thecenter line of the hob head and approximately on the line 2--2 of Fig.3;

Fig. 3 is an end view of the hob'head shown in Fig. 2, with the coverbroken away;

a is a view similar to Fig. 3 but showing; a modified construction; and

Fig. 5 is a fragmentary perspective view of the right-handside ofthemachine of Fig. 4.

Although the invention is susceptible of various modifications andalternative constructions, it is herein shown and described as embodiedin a bobbing machine similar to that shown in United States Patent No.2,307,428, issued January 5, 1943,. except that the shape of the machineis slightly different, some of the electrical control devices have beenrelocated, and the hob head is carried by a member slidably supported ina cylindrical aperture in the vertical column or frame rather than beingsupported on horizontal ways.

Generally speaking, the machine is of vertical construction andcomprises a base A, a vertical column or gooseneck B supported upon thebase A, a Work head C vertically movable upon vertically spaced pairs ofways H], H on the column B, and a tool or hob head D carried by acylindrical member slidablysupported in a horizontal cylindricalaperture inthe column B and adjustable therein towards and from the workhead. The work which may be a gear blank, a shaft to be splined, or thelike,is adapted to be rotatably supported in the Work head C by a chuckor some other suitable means, not shown, attached to the upper end 'ofthe work spindle l2 and a tail center It carried by a tailslide itsupported for vertical movement towards and from the work spindle uponways 15, IE formed on the workhead. The hob spindle or arbor ll isrotatably supported in the hob head D in a manner hereinafter morespecifically described and during operation of the machine is rotated intimed relationto the rotation of the work spindle H by a cut motorlocated in the lower part of the column 13 and operatively connected tothe respective spindles in a manner similar to that disclosed in theaforesaid patent.

The work head C is adapted to be reciprocated along the verticallyspaced pairs of ways It, H to cause a work blank carried by the workhead to be moved axially past a hob fixed to the hob arbor and to returnthe work head to its initial position bya cooperating lead screw and nutconnected to the work head C and the base A, respectively. The leadscrew is located within the chip gua-rd 2i! and is driven at arelatively slow speed in timed relation to the rotation of the hob andwork spindles from the work spindle drive. The nut is rotatablysupported in a housing 21 bolted to the base A and is adapted to berotated at-a relatively high speed through the medium of a self-lockingworm and worm wheel drive by a high speed reversible traverse motorlocated within the column B and connected thereto by the shaft 22.

, The control circuits for the respective motors, and the cycle ofoperations of the machine are preferably similar to those disclosed inthe aforesaid patent and will not be herein described in detail. Sufficeit to say that after a suitable blank has been positioned in the workhead C, the start push button switch 23 is depressed, whereupon thetraverse motor is operated to move the work head vertically at a rapidtraverse rate to bring the blank to cutting position with respect to thehob. At this point in the cycle, the traverse motor is automaticallystopped and the cut motor started, thus continuing the movement of thework head but at a relatively slow feed rate. The feed movementcontinues until the blank is cut, whereupon the cut motor isautomatically stopped. After the work has been removed from the workhead, the work head is returned to its original position by againdepressing the start push button switch to actuate the traverse motor inthe opposite direction. The direction in which the cycle of operation isperformed depends upon the setting of the selector controller switches24, 25. The machine can be stopped at any time during its cycle ofoperations by depressing the stop push button switch 26. The length oftravel of the rapid traverse approach movement, the feed movement, etc.,is controlled by the adjustable stops 3!), 3! and 32 carried by the workhead C and adapted to actuate limit switches within the housing 33.

The cylindrical member 34 which carries the hob head D is slidablysupported in the column B concentrically with respect to the main driveshaft 35 of the machine and is adapted to be moved longitudinallytherein to adjust the hob towards and from the work spindle by a screw36. The member 34 is adapted to be clamped in any adjusted position byclamp mechanism actuated by a clamp screw 31 and is prevented fromrotating in the cylindrical aperture by a key 38. The hob head Dcomprises a hob head housing 49 having a cylindrical portion 4|projecting into a cylindrical aperture in the front end of the member 34and through the medium of which the housing 40 and in turn the hob headD are rotatably connected to the front end of the member 34 concentricwith the axis of the shaft 35. The hob head D is adapted to be securedin any desired angular position by bolts 42, the heads of which engagewithin a circular T-groove 43 in the front face of the member 34.

The hob arbor I1 is slidably supported in a sleeve member 54 and throughthe medium of a sleeve 45 on the left-hand end thereof as viewed in Fig.2, in a bushing 46 of an outboard support,

designated generally as 4?. The hob H, the outline of which is shown inFig. 2, is keyed to the arbor H and interposed between the sleeve 45 anda hob spacing washer 39, the right-hand side of which abuts a shoulderformed on the arbor by a change in its diameter. The sleeve 44 isrotatably supported in the hob head housing 40 by anti-friction bearingsd8, 49 and both the hob arbor ll and the sleeve 44 are driven by a hobarbor gear 50 splined to the right-hand end of the arbor W and connectedto an external flange on the right-hand end of the sleeve 44 by machinescrews The gear 50 is continuously in mesh with a hob head drive pinion52 formed on the right-hand end of a shaft 53 rotatably supported in thehousing 40 by antifriction bearings 54, 55. The left-hand end of theshaft 53 is provided with a bevel gear 56 keyed thereto and continuouslyin mesh with a bevel drive gear 51 having an elongated hub 58, throughthe medium of which the gear is rotatably supported by anti-frictionbearings 59 in a bearing cap or member 60 connected by screws 55 to therear end of the cylindrical housing 40. The gear 5? is splined to thefront end of the main drive shaft 35 of the machine so as to permitadjustment of the hob head towards and from the Work spindle.

The sleeve 44 and the gear 50 fixed thereto are held against axialmovement relative to the housing it by the bearings 48, 49 and the hobarbor is adapted to be reciprocated therein by a threaded shaft or hobarbor screw 62 extending into an aperture 63 in the right-hand end ofthe hob arbor, the end portion 64 of which aperture is threaded toengage the threads of the screw 62. The screw 52 is rotatably secured tothe hub 65 of the gear 5i] which projects to the right beyond thehousing as and by a cap member 66 bolted to the end of the hub 65 andforming therewith a groove within which a flange 5'! on the screw isconfined. A spring 68 interposed between the end of the screw 62 and thebottom of the aperture 63 provides means for eliminating lost motionbetween the cooperating threads of the screw 52 and the hob arbor.

The hob arbor ii and the screw 52 are operatively connected by mechanismwhich pro duces a relatively slow relative rotation therebetween uponrotation of the hob arbor. As shown, this mechanism comprises anepicyclio gear train comprising a gear re keyed to the member 66 by akey M and continuously in mesh with the larger of two relatively fixedgears l2, l3 keyed to a sleeve M rotatably supported on the shank of abolt '55, the head of which engages within a radially elongated T-slot16 in a disk-like member l! rotatably supported on a flanged sleeve '18interposed therebetween and the hub es of the gear 58. The gear 113 iscontinuously in mesh with a gear 88 rotatably supported on a bolt 8!,the head of which is located within an arcuate-shaped T-slot 82 in themember F7 for adjustment towards and from the bolt ?5. lhe gear SE] iscontinuously in mesh with a gear 83 rotatably supported coaxially withthe hob arbor l? by a member 34 keyed to the screw 52 adjacent to itsright-hand end and held thereon by a nut 85.

The gear 83 is adapted to be selectively connected to the member 84 ordisconnected therefrom by a pull pin 85 slidably supported in a suitableaperture in the member 84. The righthand end of the pull pin is enlargedto form a hand grasp and the left-hand end adapted to be selectivelyengaged Within an aperture 8? in the gear 83 for the purpose of lockingthe gear 83 to the member 8 5- or permit relative rotation between themembers. The pull pin Ed is adapted to be yieldably retained in eitherits projected or retracted position by a spring-pressed pawl 88engageable within suitable grooves 33, t! in the shank of the pin. Aflange 92 on the shank of the pull pin and engageable in one position ofthe pin with the end of the member 8 and in the other position of thepin with an. inwardly projecting flange 93 on a member 94 fixed to theexterior of the member 34 limits the movement of the pull pin. Theconstruction and operation of the epicyclic gear train are such thatwhen the member l? is free to rotate on the member F8 about the axis ofthe hob arbor El, no relative rotation takes place between the hob arborand the screw 32 upon rotation of the gear 54? with the result that thehob is not advanced unless the member ll is held against ro- 5 -tation.Obviously this may be accomplished in any suitable manner. As shown inthe embodi ment illustrated in Figs. 1 to 3, rotation of the member 71:and in turn the gear cluster or assembly comprising the gears 12 and itabout the axis of rotation of the hob arbor is prevented by an anchorstud 95 threaded into the housing 4'9 and comprising a head projectinginto a slot 95 in the exterior of the member T5. The epi cyclic gearingis rendered inoperative to advance the hob arbor upon removal of theanchor stud 95. As an illustration of the type of hob advancecontemplated by the present invention, the gears lii, I2, 13, 8E} and:83 of the embodiment shown have eigh ty, twenty-nine, twenty-five,thirty-two and sixty-nine teeth, respectively, withthe result that thescrew is rotated approximately one revolution relative to the hob arborfor each two thousand revolutions of the hob arbor and since the screw62 has ten threads per inch, the hub is advanced one-tenth of an inchfor each two thousand revolutions thereof. After the hob has beenadvanced an amount equal to its usable length, the direction of axialmovement thereof can be reversed, if desired, by inserting an idler rgear in the epicyclic gear train, or it can be returned to its initialposition by manually withdrawing thepull pin 3% and turning the screw 62by hand. After the hob arbor has been returned to its starting position,the pull pin is reengaged in the aperture 8'! in the 33 and the deviceis conditioned to start a new cycle of operations. As will be wellunderstood by those skilled in the art to which the invention relateswhen the hob is continuously advanced during the cutting operation, thehob advance movement must be taken into consideration in deterrn g thegear ratios to be employed between the hob and work spindles.

As previously suggested, means otherthan that described above may beemployed for selectively holding the member ill stationary or permittingit to rotate and an alternative construction is shown in Figs. 4 and 5wherein the member ll, similar to the member ":l' of the embodimentshown in Figs. 1 to 3, is adapted to be heldstationary by asolenoid-operated brake Hit, the solenoid [iii of which is periodicallyenergized to engage the brake and advance the :hob a small amount intimed. relation to the reciprocation or" the worl: head and duringinterval when the work is out of engagement with the hob. The solenoidit i is connected in series circuit to a source of electric current withtwo normally open switches 652. are connected in parallel with eachother, which switches are adapted to be intermittently closed for ashort period of time while the cut motor is operating but while the hobis out of engagement with the work by elongated members HM, its,respectively, adjustably connected to the lower right-hand side of thework head C. The two switches m2, 5% are used because the machine showncan be operated with the w '2: head in either the up or down posi- Theconnections to the electrical switches m2, M3 are made through theselector controller switch it in such a manner that the correct switchis operatively connected in the circuit automatically with the selectionof the cycle desired. The members H24, 185 can be so located that thehub is advanced either just before the cutting operation starts orimmediately at the end thereof.

From the foregoing description of therpreferred at the beginning or thecycle or operations.

embodiments of the invention, it will be apparent that the objectsheretofore enumerated and others have been accomplished and that therehas been provided a novel hob head and bobbing machine wherein the hobis advanced during operationof the machineat a comparatively slow rateeither continuously or intermittently, as desired.

The preferred embodiments of the invention have been shown and describedwith considerable ydetai-lbut it is to be understood that the inventionis not limited to the particular construction shown and it ismyintention to hereby coverall adaptations, modifications and usesthereof which come within the practice of those skilled :in the art towhich the invention relates and within the spirit and scope of theappended claims.

Having thus described my invention, what I claim is:

1. In a hob head, the combination of a rotatable and axially movable hobarbor, means for rotating said hob arbor, a member rotatably supportedcoaxially with respect to said hob arbor, means operatively connectingsaid hob arbor and said member for moving said hob arbor axially uponrelative rotation between said'hob arbor and said member, a gear trainoperatively connected to said hob arbor and to said member andcomprising two relatively fixed gears supported for rotation about anaxis oiiset from the axis of rotation of said hob arbor for producing ;aslow relative rotation betweensaid hob arbor and said member uponrotation of said hob arbor, and means for disconnecting said geartrain.

2. In a hob head, the combination of a housing, a hob arbor, bearingmeans carried by said housing to journal said hob arbor in said housingfor rotation and axial movement relative thereto, drive means withinsaid housing forrotating said hob arbor, a member rotatably supported insaid housing and restrained from axial movement with respect thereto,means operatively connectin said hob arbor and said member for slowlymoving said hob arbor axially relative to said bearing means uponrelative rotation between said hob arbor and said member, and a geartrain operatively connected to said drive means and to said memberadapted for producing a slow rela- .tive rotation between said hob arborand .said

member upon rotation of said hob arbor.

3. In a hob head, the combination of: a rotatable and axially movablehob arbor; means for rotating said hob arbor; a member rotatablysupported coaxially with respect to said hob arbor; means operativelyconnecting said hob arbor and said member for moving said hob arboraxially upon relative rotation between said hob arbor and said member;anda gear train .operatively connected to said hob arbor and. to saidmember adapted for producing a slow relative rotation between said hobarbor and said member upon rotation of said hob arbor; said gear traincomprising a gearconcentric with said hob arbor and rotatable therewith,a gear concentric with said hob arbor and rotatable with said member,and gearing connecting saidgears.

4. In a hob head, the combination of: a rotatable and axially movablehob arbor; means for rotating said hob arbor; a member rotatablysupported coaxially with respect to said hobarbor; meansoperativelyconnecting-said hob arbor-and said member for moving said hob arboraxially upon relative rotation between said hob arbor and said member; agear train operatively connected to said hob and. to saidmember-forproducing slow relative rotation between said hob arbor andsaid member upon rotation of said hob arbor; said gear train comprisinga gear concentric with said hob arbor and rotatable therewith, a gearconcentric with said hob arbor and rotatable with said member, andgearing connecting said gears; and means for renderin said gear traininefiective to produce said slow relative rotation between said hobarbor and said member.

5. In a hob head, the combination of a rotatable and axially movable hobarbor, means for rotating said hob arbor, a member rotatably supportedcoaxially with respect to said hob arbor, means for operativelyconnecting said arbor and said member for moving said hob arbor axiallyupon relative rotation between said hob arbor and said member, a secondmember rotatably supported coaxially with said hob arbor, means forselectively holding said second member stationary, a gear trainoperatively connected to said hob arbor and to said first-lnentio.nedmember and comprising gearing supported by said second member forrotation about an axis offset from the axis of rotation of said hobarbor for producing a slow relative rotation between said hob arbor andsaid first-named member upon rotation of said hob arbor.

6. In a hob head, the combination of: a rotatable and axially movablehob arbor; means for rotating said hob arbor; a member rotatably sup"ported coaxially with respect to said hob arbor for moving said hobarbor axially upon relative rotation between said hob arbor and saidmember; a second member rotatably supported coaxially with respect tosaid hob arbor; means for selectively holding said second memberstationary; and a gear train operatively connected to said hob arbor andto said firstmamed member for producing a slow relative rotation betweensaid hob arbor and said first-named member upon rotation of said hobarbor, said gear train comprising a gear concentric with said hob arborand rotatable therewith, a. gear concentric with said hob arbor androtatable with said first-- named member, and gearing carried by saidsecond member connecting said gears.

7. In a hobbing machine, the combination of a rotatable and axiallymovable hob arbor, a rotatable work support, means for rotating said hobarbor and said work support, means for producing a relative movementbetween said hob arbor and said work support axially of the of rotationof said work support, a member rotatably supported coaxially withrespect to said hob arbor, means operatively connecting said hob arborand said member for moving said hob arbor axially upon relative rotationbetween said hob arbor and said member, a second member rotatablysupported coaxially with respect to said hob arbor, means controlled bythe relative movement between said hob arbor and said work sup portaxially oi the axis rotation of said work support for intermittentlyholding said second member stationary, and a gear train comprisinggearing carried by said second member for rotation about an axis offsetfrom the axis of rotation of said hob arbor for producing siow relativerotation between said hob arbor and firstnamed member upon rotation ofsaid hob arbor.

8. In a hobbing machine, the combination of a rotatable and axiallymovable hob arbor, a rotatable work support, means for simultaneouslyrotating said hob arbor and said work support in predetermined timedrelation during the hobbing operation, means for producing a relativemovement between said hob arbor and said work support axially of theaxis of rotation of said work support during the hobbing operation andin predetermined timed relation to the rotation of said hob arbor andsaid work support, a member associated with said hob arbor and supportedfor rotation relative thereto, means operatively connecting said hobarbor and said member for moving said hob arbor axially upon relativerotation between said hob arbor and said member, and gearing meansinterconnecting said member and the driving means for the arbor toproduce a slow relative rotation between said hob arbor and said memberduring the hobbing operation and in predetermined timed relation to therotation of said hob arbor.

9. In a hobbing machine, the combination of a rotatable and axiallymovable hob arbor, a rotatable work support, means for rotating said hobarbor and said work support in predetermined timed relation durin thehobbing operation, means for producing a relative movement between saidhob arbor and said work support axially of the axis of rotation of saidwork support during the hobbing operation and in predetermined timedrelation to the rotation of said hob arbor and said work support, amember rotatably supported coaxially with respect to said hob arbor,means operatively connecting said hob arbor and said member for movingsaid hob arbor axially upon relative rotation between said hob arbor andsaid member, a second member rotatably supported coaxially with respectto said hob arbor, means for selectively holding said second memberstationary, and a gear train operatively connected to said hob arbor andto said first-named member and comprising gearing carried by said secondmember for rotation about an axis oifset from the axis of rotation ofsaid hob arbor for producing a slow relative rotation between said hobarbor and said first-named member.

1.0. In a hobbing machine, the combination of a rotatable work. support,a hob head, a rotable hob arbor journaled in said head for rotation andaxial movement relative thereto, means for rotating said support andarbor in timed relation to each other and for producing relative linearmovement between said support and arbor in a direction parallel with theaxis of rotation of the work support, a rotatable member journalled insaid head and restrained from axial movement with respect thereto,gearing within said head driven by said first-mentioned means forproducing a slow relative rotation between said arbor and said member,and means including cooperating threaded parts op-erativelyinterconnecting aid arbor and member whereby said arbor is slowly movedaxially relative to said head in response to relative rotation betweensaid arbor and member.

11. In a hobbing machine, the combination of an angular-1y adjustablehousing, a hob arbor, bearing means carried by said housing to journalsaid hob arbor in said housing for rotation and axial movement relativethereto, a rotatable work support, means for simultaneously rotatingsaid hob arbor and said work support in predetermined timed relationduring the hobbing operation, means for producing a relative feedmovement between said hob arbor and said work support axially of theaxis of rotation of said work support during the hobbing operation andin predetermined timed relation to the rotation of said hob arbor andsaid work support, a member rotatably supported in said housing andrestrained from axial movement with respect thereto, gearing meansoperatively connecting said hob arbor and said member for effecting aslow relative rotation between said arbor and memher, and meansoperatively interconnecting said arbor and member for moving said hobarbor axially relative to said bearing means upon rela tive rotationbetween said hob arbor and said member.

12. In a hob head, the combination of an angularly adjustable housing, ahob arbor supported by said housing for rotation and axial movement,drive means carried by said hOLlSlIlg for rotating said hob arbor,cooperating threaded parts one fixed to and rotatable with said hobarbor and the other rotatable relative to said housing and restrainedfrom axial movement relative thereto for producing axial movement ofsaid hole arbor upon relative rotation between said parts, and gearingmeans operatively connected to said drive means and the other of saidthreaded parts for producing a slow relative rotation between saidthreaded parts.

13. In a hob head, the combination of a housing, a hob arbor supportedby said housing for rotation and axial movement, drive means including adriven member concentric with said hob arbor for rotating said hobarbor, cooperating threaded parts operatively connected to said hobarbor for moving said hob arbor axially relative to said housing, one ofsaid threaded part being connected for rotation with said arbor and theother of said parts being supported for rotation relative to said arbor,eans rotatably interconnecting said housing with one of said threadedparts in a manner preventing axial movement thereof, and earing meansoperatively connected to said driven member and that threaded part whichis rotatable relative to said arbo for producing a slow relativerotation between said threaded parts.

14. In a hob head, the combination of an angularly adjustable housing, ahob spindle assembly including a rotatable member and a coaxial hobarbor supported for axial movement within said member, drive meanscarried by said housing for rotating said hob spindle assembly,cooperating threaded parts for producing axial movement of said hobarbor relative to said member upon relative rotation between saidthreaded parts, one i of said threaded parts being operatively connectedto said hob arbor, and a gear train operatively connecting said memberto the other of said threaded parts for producing a slow relativerotation between said threaded parts.

15. In a hob head, the combination of a housing, a hob spindle assemblyincluding a rotatable member and a hob arbor supported for axialmovement within said member, drive means carried by said housing forrotating said hob spindle assembly, cooperating threaded parts oneoperatively connected to said member and the otherfixed to and rotatablewith said hob arbor for movin said hob arbor axially relative to saidmember, and means for operatively connecting said member and said firstthreaded member comprisin a gear fixed to said member, a second gearfixed to said first-named threaded part and concentric with said firstgear and said hob arbor, and gears operatively connected to said gearsfor producing a slow relative rotation between said threaded parts.

16. In a hob head, the combination of a housing, a hob spindle assemblyincluding a rotatable member and a hob arbor supported for axial 10movement within said member, drive means carried by said housing forrotating said hob spindle assembly, cooperating threaded partsconcentric with the axi of rotation of said hob arbor for producing aslow axial movement of said hob arbor relative to said member uponrelative rotation between said threaded parts one of said threaded partsbeing fixed to and rotatable with said hob arbor, a gear fixed to saidmember, a second gear fixed to said second-mentioned threaded part, andgearing operatively connectin said gears whereby said second-mentionedthreaded part is rotated relative to said firstmentioned threaded partupon rotation of said hob spindle assembly.

17. In a hob head, the combination of; a housing; a hob spindle assemblyincludin a rotatable member, a hob arbor supported for axial movementwithin said member cooperating threaded parts one fixed to and rotatablewith said hob arbor; a gear fixed to said member; a second gear fixed tosaid threaded part other than the part fixed to said hob arbor; meansfor rotating said spindle assembly; and gear means for connecting saidfirst two mentioned gears including a pair of gears rotatable about anaxis fixed with respect to said housing.

18. In a bobbing machine, the combination of a rotatable work support, ahousing pivotally supported for adjustment about an axis extendingtransversely of the axis of rotation of said work support, a hob arborsupported by said housing for rotation and axial movement, drive meansfor simultaneously rotating said hob arbor and said work support inpredetermined timed relation, said drive means including gearin Withinsaid housing and connected to a shaft coaxial with the pivotal axis ofsaid housing, means for producing simultaneously with the rotation ofsaid hob arbor and said work support a relative feed movement betweensaid hob arbor and said work support axially of the axis of rotation ofsaid work support in predetermined timed relation to the rotation ofsaid hob arbor and said work support, relatively rotatable threadedparts operatively connected to said hob arbor for moving said hob arboraxially, one of said threaded parts being connected for rotation withsaid arbor and the other of said parts bein supported for rotationrelative to said arbor, means rotatably interconnecting aid housing withone of said threaded parts in a manner preventing axial movementthereof, and a gear train operatively connecting said gearing withinsaid housing to that threaded part which is rotatable relative to saidarbor for producing a slow relative rotation between said threaded partsin predetermined timed relation to the rotation of said hob arbor.

THEODORE F. CARLIN.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,140,610 Reinecker May 25, 19152,122,219 Staples June 28, 1938 2,219,134 Staples Aug. 6, 1940 2,374,255Davenport Apr. 24, 1945 FOREIGN PATENTS Number Country Date 331,343Great Britain July 3, 1930

